The subject invention relates to a mat that is given more dimensional stability through the inclusion of binder and to the method of making the dimensionally more stable mat through a unique application of the binder to the mat.
Mats are commonly used in the roofing and other industries to reinforce laminates, membranes, shingles, roll roofing, etc. and provide these articles with dimensional stability. For example, in the roofing industry, single ply roofing membrane systems are commonly used as the roofing systems for low sloping roofs, especially in industrial and commercial applications. These single ply roofing membrane systems utilize roofing membranes that each include two thermoplastic olefin (“TPO”) sheets bonded to each other and to a dimensionally stable reinforcing mat. To meet industry standards, these roofing membranes typically have a maximum linear dimensional change of plus or minus 2% as measured by ASTM D 1204, 6 hours at 158° F./70° C.; and a minimum puncture resistance as measured by ASTM D 4833 of 90 pounds of force at 73° F./23° C. The reinforcing mats used to reinforce these roofing membranes, to reinforce other roofing products, and to reinforce various laminates and membranes used for other non-roofing applications may be woven or unwoven mats of staple fibers and/or continuous filaments and include a binder that is evenly distributed throughout the mats to give the mats the required dimensional stability for a particular application. While these mats perform quite well as reinforcements for various laminates, membranes, etc., there is a need for lower cost dimensionally stable mats.
U.S. Pat. No. 5,865,003 discloses a reinforced glass fiber mat made in a wet process that has a predetermined pattern of relatively high and low concentrations of binder throughout the length of the glass fiber mat and a method of forming the mat wherein, in a wet process, binder is either selectively applied only to portions of the mat via an applicator or selectively removed from portions of the mat via a vacuum. However, the need remains for reduced cost reinforced fiber mats, with relatively high and low binder concentrations, which do not require the selective application or vacuum removal of binder.